12ac Railroad is not the definition - this is one of the 6 pairs and so is undefined.
The last 2 letters 'EL' refer to the elevated railways in USA; they are known as 'Ls'.
Afternoon all - completely forgot about this crossword until I saw the 2 threads on here today. A pleasurable afternoon spent on it. Some very nice clues!
AJT - I hope you are now over all your disasters and can spare time for crosswords again!